1. Field of Invention
This invention relates to substrates for electrostatographic imaging members. This invention also relates to a method of making the substrates.
2. Discussion of Related Art
Substrates for electrostatographic imaging members including electrographic and electrophotographic imaging members have been formed by electroforming methods. For example, these methods have been used to form flexible, seamless electrostatographic substrates such as substrates for photoreceptors. Such photoreceptor substrates have been manufactured by electroforming a metallic material onto a mandrel immersed in an electrolytic bath, to produce an electroformed layer or form on the mandrel. For example, photoreceptor substrates have been formed from nickel-based materials, which provide desirable substrate properties in photoreceptors.
The forms are commonly cylindrical shaped and of a constant diameter. The forms can be removed from the mandrels by either selectively dissolving the mandrel, or by removing the form from the mandrel. To permit removal of the form from the mandrel upon cooling of the assembly, the form and mandrel can be formed of materials having different coefficients of thermal expansion. Exemplary mandrels and electroforming processes are disclosed, for example, in U.S. Pat. No. 3,844,906 to Bailey et al.; U.S. Pat. No. 4,067,782 to Bailey et al.; U.S. Pat. No. 4,501,646 to Herbert and U.S. Pat. No. 4,902,386 to Herbert et al., each incorporated herein by reference in its entirety.
Non-ferromagnetic and ferromagnetic developer systems are used in electrostatographic apparatus. Ferromagnetic developer systems include magnetic brushes and magnetic toners in single and two-component developers.
In apparatus that include ferromagnetic developer systems, it is known to form the substrate of the imaging member of a non-ferromagnetic material. Aluminum is commonly used to form such non-ferromagnetic substrates. Aluminum is also used to form substrates of electrostatographic imaging members used in apparatus including non-ferromagnetic developer systems.
Aluminum substrates are formed by extruding aluminum and honing theextrusions to the desired dimensions. Thus, secondary operations are required to achieve the desired dimensional tolerances of the aluminum substrates. In addition, the aluminum substrates are subjected to secondary operations, such as particle blasting, to achieve a desired surface finish and to cleaning steps.
As explained above, both ferromagnetic and non-ferromagnetic developer systems are known for use in electrostatographic imaging apparatus. Ferromagnetic developer systems use magnetic toners and magnetic brushes. Ferromagnetic substrates in known electrostatographic imaging members provide improved sensitivity and an improved ability to print single pixel lines.
However, the improved sensitivity that enables such fine line copying can cause a reduction in the number of discernible density levels in images. This can cause darker halftones to appear totally black. Toner consumption can also be increased, resulting in thicker images than desired. Other development latitude can also be affected by the ferromagnetic substrates. For example, bias and/or scorotron-to-photoreceptor spacing is sometimes needed to achieve good prints or copies.
The improvement in fine line development as well as the loss in development latitude is attributed to the magnetic fields that are generated by and/or impacted by the ferromagnetic substrates.
Non-ferromagnetic substrates are most commonly used in the electrostatographic imaging members. However, although the use of such known non-ferromagnetic substrates in such magnetic developer systems may provide a satisfactory solution to some of the above-described problems of ferromagnetic substrates, the known non-ferromagnetic substrates have other associated problems. As explained above, aluminum non-ferromagnetic substrates are not cost effective to produce because they require machining and finishing operations to achieve suitable dimensional tolerances and finishes to enable the substrates to be used in electrostatographic imaging members.
Electroforming methods provide important cost advantages compared to the above-described methods for forming substrates such as aluminum substrates. Particularly, electroforming can be used to form substrates having exact dimensional tolerances at a lower cost than the methods used to form such aluminum substrates. In addition, the electroformed substrates do not generally require any secondary cleaning or surface finishing operations to achieve a desired surface finish.
As stated above, electroformed nickel substrates are known for use in photoreceptor belts. However, these known nickel substrates are ferromagnetic. Accordingly, when such nickel substrates are used in combination with magnetic developer systems, the above-described problems with regard to print quality will occur.
This invention provides non-ferromagnetic substrates suitable for use in electrostatographic apparatus that include magnetic developer systems.
This invention separately provides nickel-based substrates that can be used in combination with magnetic developer systems and that do not adversely interact with such magnetic developer systems.
This invention separately provides nickel-based substrates that can be used in combination with magnetic developer systems, such that fine line development and reduced toner consumption are achieved.
This invention separately provides non-ferromagnetic substrates formed by electroforming.
This invention separately provides non-ferromagnetic substrates that are formed cost effectively and with exacting dimensional tolerances.
This invention separately provides non-ferromagnetic substrates that are electroformed using conventional electroforming techniques.
This invention separately provides processes for forming the improved non-ferromagnetic substrates.
One exemplary embodiment of the method of electroforming a non-magnetic substrate for use in an electrostatographic imaging member of this invention comprises placing a mandrel in an electroforming electrolyte in an electrolytic cell, where the electrolyte comprises nickel and one of phosphorus, tin and copper. Current is applied to activate the electrolytic cell to electroform a non-magnetic substrate comprising nickel and phosphorus, tin or copper. The substrate can be removed from the mandrel by conventional techniques such as cooling the mandrel and substrate.
One exemplary embodiment of the substrates according to the methods of this invention are cylindrical shaped and seamless. Such substrates can be used in electrostatographic imaging members including electrographic imaging members and photoreceptors. The substrates do not adversely interact with magnetic brushes and magnetic toners.